Electrochromic Films and Related Methods Thereof

ABSTRACT

EC film stacks and different layers within the EC film stacks arc disclosed. Methods of manufacturing these layers are also disclosed. In one embodiment, an EC layer comprises nanostructured EC layer. These layers may be manufactured by various methods, including, including, but not limited to glancing angle deposition, oblique angle deposition, electrophoresis, electrolyte deposition, and atomic layer deposition. The nanostructured EC layers have a high specific surface area, improved response times, and higher color efficiency.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/858,214, filed on Jul. 25, 2013, which is incorporated by referencein its entirety.

BACKGROUND OF THE INVENTION Field of the Invention

Embodiments disclosed herein relate to electro-chromic films and methodsand applications thereof.

Background

Electro-chromic (EC) film stacks may be applied to surfaces when it isdesirable to change the optical transmission properties of the surface.For example, the stacks may be applied to ophthalmic lenses to reducetransmission of harmful ultra-violet light through the lenses. Anelectro-chromic film stack generally comprises at least oneelectro-chromic layer in contact with at least one ion conductor layer.When a voltage is applied, ions and electrons are transferred betweenthe different layers, resulting in a change of the optical properties ofthe stack. When the voltage is turned off, the stack's opticalproperties return to the unaltered state.

Despite the large number of on-going research studies in the field ofvarious EC technologies, there is still a need of compact andmechanically-robust solid-state electro-chromic film stack, which can beeasily applied on existing ophthalmic lens blanks, semi-finished blanks(SFB), or other surfaces that need controllable variable transmissionperformance. It may also be desirable for such EC stack to operate underlower voltage, and thus, not require large, heavy and aestheticallynon-acceptable batteries. In addition, the variable-transmission ECstack should be fast-responding with a satisfactory dynamic rangecompared to the current available photochromic lenses and otherswitching technologies. Moreover, such robust EC stack has a potentialto be applied to any other large area transparent surfaces. Theseinclude but are not limited to architectural windows, glass roofs, carwindshields, and other applications that require controllabletransmission for energy-saving and other purposes.

The EC film stack should also survive all post-processing steps of thesurfaces that it is applied to. For instance, if applied to ophthalmicSFBs, it should survive the surfacing to different lens prescriptions,edging into different lens shapes and grooving steps, which is not thecase with non-solid EC devices utilizing liquid electrolytes.Furthermore, if the solid EC film stack can be deposited on a singlesubstrate, it would be very beneficial for the reduction the “bulkiness”of the final product such as but riot limited to ophthalmic lens,motorcycle helmets, and windows.

BRIEF SUMMARY OF THE INVENTION

In one embodiment, a method comprises: depositing an electro-chromicmaterial over a surface of a substrate having a surface normal to form ananostructured electro-chromic layer by exposing the surface to a fluxof the electro-chromic material traveling in a first direction. Theincident angle between the first direction and the surface normal is atleast 1 degree and at most 89 degrees.

In one embodiment, the incident angle is at least 1 degree and less than10 degrees. In one embodiment, the incident angle is at least 10 degreesand less than 80 degrees. In one embodiment, the incident angle is atleast 80 degrees and at most 89 degrees.

In one embodiment, the method comprises rotating the substrate relativeto the flux while depositing the electro-chromic material. In oneembodiment, the substrate is not rotated relative to the flux whiledepositing the electro-chromic material.

In one embodiment, the method further comprises depositing a firstion-conducting layer over the nanostructured layer after depositing theelectro-chromic material and depositing a second ion-conducting layerover the first ion-conducting layer after depositing the firstion-conducting layer to form an electro-chromic optical device.

In one embodiment, the electro-chromic material comprises twoelectro-chromic materials and the step of depositing comprisesco-depositing two electro-chromic materials over the surface.

In one embodiment, the electro-chromic material consists essentially ofa single electro-chromic material.

In one embodiment, the nanostructured electro-chromic layer comprises atleast one columnar structure.

In one embodiment, the at least one columnar structure and the normal ofthe surface form an angle that is less than the incident angle.

In one embodiment, the nanostructured electro-chromic layer has featuresizes ranging from 1 nanometer to 500 nanometers.

In one embodiment, the electro-chromic material is selected from a groupconsisting of: tungsten oxide, nickel oxide, iridium oxide, molybdenumoxide, vanadium oxide, and combinations thereof. In one embodiment, theelectro-chromic material is tungsten oxide.

In one embodiment, the formulation of a nanostructured electro-chromiclayer is accomplished by a combination of: (1) exposing the surface to aflux of the electro-chromic material traveling in a first direction, and(2) at least one of sol-gel, dip-coating, spin-coating, knife coating,annealing, and sintering.

In one embodiment, the nanostructured electro-chromic layer has aspecific surface area greater than 50 m²/g. In one embodiment, thenanostructured electro-chromic layer has a coloration efficiency ofgreater than 50 cm²/C. In one embodiment, the electro-chromic materialis selected from the group consisting of: nickel oxide, iridium oxide,molybdenum oxide, vanadium oxide, and combinations thereof.

In one embodiment, the electro-chromic layer comprises a mixture of twodifferent electro-chromic materials.

In one embodiment, a method comprises depositing a first electro-chromicmaterial over a surface of a first substrate having a first surfacenormal to form a first nanostructured electro-chromic layer by exposingthe surface to a first flux of the electro-chromic material traveling ina first direction. The incident angle between the first direction andthe first normal is at least 1 degree and at most 89 degrees. The methodfurther comprises depositing a second electro-chromic material over asurface of a second substrate having a second surface normal to form asecond nanostructured electro-chromic layer by exposing the surface to asecond flux of the second electro-chromic material traveling in a seconddirection. The incident angle between the second direction and thesecond normal is at least 1 degree and at most 89 degrees. The methodfurther comprises depositing a first ion-conducting layer over the firstnanostructured layer, depositing a second ion-conducting layer over thesecond nanostructure layer, and assembling the first substrate and thesecond substrate such that the first ion-conducting layer and the secondion-conducting layer are in contact form an electro-chromic opticalsystem.

In one embodiment, wherein the first and second nanostructured layershave the same material composition. In one embodiment, the first andsecond nanostructured layers have different material compositions.

In one embodiment, a method comprises depositing an electro-chromicmaterial over a surface of a substrate using electrophoresis ofelectro-deposition to form a nanostructured electro-chromic layer.

In one embodiment, the depositing is done by electrophoresis. In oneembodiment, the depositing is done by electro-deposition.

In one embodiment, the method further comprises depositing a pre-cursormaterial on the surface before depositing the electro-chromic materialand removing the pre-cursor material from the surface after depositingthe electro-chromic material.

In one embodiment, the precursor material comprises polystyrene.

In one embodiment, the step of depositing comprises co-depositing twoelectro-chromic materials and the nanostructured electro-chromic layercomprises a mixture of two electro-chromic material.

In one embodiment, the electro-chromic material consists essentially ofa single electro-chromic material.

In one embodiment, the nanostructured electro-chromic layer comprises atleast one columnar structure.

In one embodiment, the at least one columnar structure and the normal ofthe surface are not parallel to each other.

In one embodiment, the nanostructured electro-chromic layer has featuresizes ranging from 1 nanometer to 500 nanometers.

In one embodiment, the electro-chromic material is selected from a groupconsisting of: tungsten oxide, nickel oxide, iridium oxide, molybdenumoxide, vanadium oxide, and combinations thereof. In one embodiment theelectro-chromic material is tungsten oxide.

In one embodiment, the method further comprises at least one of sol-gel,dip-coating, spin-coating, knife coating, annealing, and sintering.

In one embodiment, the nanostructured electro-chromic layer has aspecific surface area greater than 50 m²/g. In one embodiment, thenanostructured electro-chromic layer has a coloration efficiency ofgreater than 50 cm²/C. In one embodiment, the electro-chromic materialis selected from the group consisting of: nickel oxide, iridium oxide,molybdenum oxide, vanadium oxide, and combinations thereof.

In one embodiment, the electro-chromic layer comprises a mixture of twodifferent electro-chromic materials.

In one embodiment, the formation of a nanostructured electro-chromiclayer is accomplished by a combination of: (1) depositing anelectro-chromic material over a surface using electrophoresis orelectro-deposition and (2) at lead one of sol-gel, dip-coating,spin-coating, knife coating, annealing, and sintering.

In one embodiment, an electro-chromic device comprising a substrate anda nanostructured electro-chromic layer disposed over the substrate. Theelectro-chromic layer comprises a mixture of at least two compounds,wherein both compounds are selected from the group consisting ofceramics, metals, and polymers.

In one embodiment, the first compound is different from the secondcompound.

In one embodiment, a method comprises, performing the following steps inorder: depositing a monolayer of a precursor material over a firstsurface of a substrate by exposing the first surface to a precursormaterial and exposing the first surface to a vapor reactant. Themonolayer of precursor material undergoes a reaction when exposed to thevapor reactant to form a nano-layer on the first surface.

In one embodiment, wherein the nano-layer comprises a uniform thickness.In one embodiment, the nano-layer comprises at least one nanostructure.In one embodiment, the nanostructure has at least one feature sizeranging from 1 nanometer to 500 nanometers.

In one embodiment, the nano-layer is comprised of electro-chromicmaterial. In one embodiment the electro-chromic material is tungstenoxide. In one embodiment, the electro-chromic material is selected froma group consisting of: tungsten oxide, nickel oxide, iridium oxide,molybdenum oxide, vanadium oxide, and combinations thereof. In oneembodiment, the electro-chromic material comprises a mixture of twodifferent electro-chromic materials.

In one embodiment, the formation of a nano-layer is accomplished by acombination of: (1) depositing a monolayer of a precursor material overa first surface by exposing the first surface to a precursor materialand exposing the first surface to a vapor reactant, and (2) at least oneof sol-gel, dip-coating, spin-coating, knife coating, annealing, andsintering.

In one embodiment, the nano-layer has a specific surface area greaterthan 50 m²/g. In one embodiment, the nano-layer has a colorationefficiency of greater than 50 cm²/C.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

FIG. 1A shows a schematic representation of glancing angle deposition,according to one embodiment.

FIG. 1B shows a close up of the electro-chromic flux shown in FIG. 1A.

FIG. 1C shows the incident angle on the substrate shown in FIG. 1A.

FIG. 2A show the nucleation step of angle deposition. FIG. 2B showscolumnar growth during angle deposition according to one embodiment.

FIGS. 3A-B show SEM images of some exemplary nanostructured layersobtained by GLAD.

FIG. 4 shows a schematic representation of electrophoretic depositionand electro-deposition, according to one embodiment.

FIG. 5A shows a schematic representation of electrophoretic depositionof Ni(OH)₂ powder.

FIG. 5B shows a schematic representation of electrophoretic depositionof a non-porous NiO.

FIGS. 6A-D show a schematic representation of atomic layer deposition.

FIG. 7A shows a nanostructured electro-chromic layer with a singleelectro-chromic material. FIG. 7B shows a nanostructured electro-chromiclayer with two materials prepared using the same method. FIG. 7C shows ananostructured electro-chromic layer.

FIGS. 8A-L show nanostructured electro-chromic layers with columnarstructures.

FIG. 9 shows an electro-chromic film with electro-chromic layers.

FIGS. 10A-10B show embodiments of nanostructured features.

DETAILED DESCRIPTION OF THE INVENTION

A major challenge in the performance of the all-solid-state EC devicesis their slow response. However, if the solid EC layers are fabricatedin such a way to consist of nanostructures with a large specific surfacearea, then the ions from the neighboring ion-conductive layers and/orion-conductive electrolyte would have “an easy access” to the activesites in the EC layers, and thus, the EC stacks would show fast coloringand bleaching response, as well as high CE.

Embodiments disclosed herein relate to EC film stacks and methods ofmaking the layers or films within the EC film stacks. Additionally,embodiments disclosed herein relate to nanostructured EC layers that maybe incorporated into the film stacks with fast response and high colorefficiency (CE). They may be of purely inorganic or organic or hybridnature. Furthermore, the EC layers may consist of a single material ormultiple materials. Embodiments disclosed herein also relate to methodsof making nano-layer films including methods of making nanostructuredfilms that that are faster and less-expensive ways of fabricatingnanoscale-structured thin films compared to the traditional proceduresof patterning and etching of bulk films.

The resulting EC film stacks have significantly faster response andimproved coloration efficiency (CE) under externally applied voltagecompared to bulk EC crystalline or amorphous films. These solidelectro-chromic (EC) film stacks may be added or directly deposited onlens blank or SFB or other surface that needs controllable variabletransmission property.

The following description recites various aspects and embodiments of thepresent invention. No particular embodiment is intended to define thescope of the invention. Rather, the embodiments merely providenon-limiting examples of various apparatuses, compositions, and methodsthat are at least included within the scope of the invention. Thedescription is to be read from the perspective of one of ordinary skillin the art therefore, information well known to the skilled artisan isnot necessarily included.

Additionally, the foregoing description of the specific embodiments willso fully reveal the general nature of the invention that others can, byapplying knowledge within the skill of the art, readily modify and/oradapt for various applications such specific embodiments, without undueexperimentation, without departing from the general concept of thepresent invention. Therefore, such adaptations and modifications areintended to be within the meaning and range of equivalents of thedisclosed embodiments, based on the teaching and guidance presentedherein. It is to be understood that the phraseology or terminologyherein is for the purpose of description and not of limitation, suchthat the terminology or phraseology of the present specification is tobe interpreted by the skilled artisan in light of the teachings andguidance.

As used herein, the term “comprise,” “comprises,” or “comprising”implies an open set, such that other elements can be present in additionto those expressly recited. As used herein, “consisting essentially of”implies a closed set. However, the closed set may include impurities andother variances that do not materially affect the basic characteristicsof the closed set.

As used herein, the articles “a,” “an,” and “the” include pluralreferents, unless expressly and unequivocally disclaimed.

As used herein, the conjunction “or” does not imply a disjunctive set.Thus, the phrase “A or B is present” includes each of the followingscenarios: (a) A is present and B is not present; (b) A is not presentand B is present; and (c) A and B are both present. Thus, the term “or”does not imply an either/or situation, unless expressly indicated.

FIG. 9 shows an exemplary EC device with an exemplary EC film stack 1000according to one embodiment. As used herein, an EC film stack refers toa multi-layer structure exhibiting EC properties, meaning that itreversibly changes color upon the application of an electric potential,or reversible changes color upon changing the magnitude of the electricpotential applied. In some embodiments, the EC film stack is a structurethat is transparent when no electric potential is applied to the stack,meaning that it transmits 75%, or at least 80%, or at least 90%, or atleast 95%, or at least 97%, or at least 99% of visible light. In someembodiments, the EC film stack is a structure that when the electricpotential is applied, blocks at least 10%, or at least 20%, or at least30%, or at least 40%, or at least 50%, or at least 60%, or at least 70%of visible light. In some embodiments, the blocking is substantiallyuniform across the visible electromagnetic spectrum, in otherembodiments it is not.

LC film stack 1000 comprises EC layers or films 2000A and 2000B, ionconducting intermediate layers 3000A and 3000B, ion conducting layer4000A and 4000B, and electrodes 5000A and 5000B. While EC film stack1000 is shown disposed between two substrates 6000A and 6000B, EC filmstack 1000 may be disposed over only one substrate 6000A. Where a firstlayer is described as “disposed over” or “deposited over” a secondlayer, the first layer is disposed or deposited farther away from thesubstrate. Additionally, there may be other layers between the first andsecond layer, unless it is specified that the first layer is “in contactwith” the second layer. For example, an EC layer may be described as“disposed over” a substrate 6000, even though there are various otherlayers in between. When successive layers discussed herein are describedas being disposed over each other, this is in reference to a singlesubstrate regardless of whether or not a device may include more thanone substrate. The substrate in which successive layers are disposedover will be apparent from the description and/or the figures. A layerthat is disposed over a substrate or layer is not necessarily depositedover that substrate or layer. If a first layer is deposited over asecond layer, the second layer must be present before the first layer isdeposited over it.

As used herein, a “film” and a “layer” may be interchangeable.

In some embodiments, substrate 6000 is an “optical substrate.” As usedherein, the term “optical substrate” refers to any substrate suitablefor use as a lens or lens blank (including semi-formed lens blank), orsuitable for being formed into a lens or lens blank. In general, theoptical substrate is a transparent material, meaning that it transmitsat least 75%, or at least 80%, or at least 85%, or at least 90%, or atleast 95%, or at least 97%, or at least 99% of visible light. Theinvention is not limited to any particular material, so long as thematerial is suitable for use as an optical substrate. Suitable materialsinclude, but are not limited to, glass, quartz, or a polymeric material,such as polycarbonate. The material can have any index of refractionsuitable for use in optical applications. The substrate may also includeother coatings or films, as are well known in the field to which theinvention is directed.

In some embodiments, the optical substrate is a lens, such as a lens foruse in a pair of spectacles. As used herein, a “lens” is any device orportion of a device that causes light to converge or diverge (i.e., alens is capable of focusing light). A lens may be refractive ordiffractive, or a combination thereof. A lens may be concave, convex, orplanar on one or both surfaces. A lens may be spherical, cylindrical,prismatic, or a combination thereof. A lens may be made of opticalglass, plastic, thermoplastic resins, thermoset resins, a composite ofglass and resin, or a composite of different optical grade resins orplastics. It should be pointed out that within the optical industry adevice can be referred to as a lens even if it has zero optical power(known as plano or no optical power). In these cases, the lens can bereferred to as a “plano lens.” A lens may be either conventional ornon-conventional. A conventional lens corrects for conventional errorsof the eye including lower order aberrations such as myopia, hyperopia,presbyopia, and regular astigmatism. A non-conventional lens correctsfor non-conventional errors of the eye including higher orderaberrations that can be caused by ocular layer irregularities orabnormalities. The lens may be a single focus lens or a multifocal lenssuch as a Progressive Addition Lens or a bifocal or trifocal lens.

In other embodiments, substrate 6000 is not an ophthalmic substrate.These substrates include any substrate through which light travels to inits path to the eye. Some non-limiting examples include car windshields,building windows, and the like. Additionally, these substrates may alsoinclude glass substrates that may be affixed to ophthalmic substrates.As used herein, “glass” refers to an amorphous inorganic solidtransparent material. It generally includes a major amount of siliconoxide, and can have minor amounts of other metal oxides, including, butnot limited to, oxides of calcium, aluminum, magnesium, and sodium.Other oxides and dopants can be present as well. These substrates likethe ophthalmic substrates, may also include other coatings or films, asare well known in the field to which the invention is directed.

While one ion conducting layer 4000 and two ion conducting intermediatelayers 3000 are shown, EC film stack 1000 may have more or less layers.For example, EC film stack 1000 may have two conducting layers and nointermediate layers or one ion conducting layer and no intermediatelayers. Additionally, while ion conducting intermediate layers 3000 areshown with a certain contour and depth, embodiments disclosed herein arenot limited to this contour and depth. This is described in more detailin application Ser. No. 14/332,180 which is incorporated by reference inits entirety.

The EC film stack disclosed herein should survive all post-processingsteps of the surfaces that it is applied to. For instance, if applied toophthalmic SFBs, it should survive the surfacing to different lensprescriptions, edging into different lens shapes and grooving steps,which is not the case with non-solid EC devices utilizing liquidelectrolytes.

EC film stacks disclosed herein respond significantly faster to anexternally applied voltage compared to EC film stacks comprising bulk ECcrystalline or amorphous films. They also have improved colorationefficiency (CE). In one embodiment, EC film stack 2000 may have adynamic response of less than 30 seconds and a high CE greater than 50cm²/C. In the visible spectral range. As used herein the visiblespectral range is from 400 nm-700 nm. These advantages are present evenunder low voltages, such as voltages equal or less than 4 Volts.

The response time and CE of an EC film stack is dependent on manyfactors, including but not limited to, the specific surface area of theEC layer. A higher specific surface area may improve response time andCE because it allows for more active sites on the EC layers and “easyaccess” of neighboring ion-conductive layers and/or ion-conductiveelectrolytes. Thus, one way to characterize the responsiveness of an ECfilm is through the specific surface area of the EC layer.

Specific surface area is related to total surface area and may bedefined as the total surface area of a solid material, film, or coating,per unit of its mass. One way to measure this parameter is by theBrunauer-Emmett-Teller (BET) theory, which is based on the physicalabsorption of gas molecules on the solid material, film, or coating.Unless disclosed otherwise, specific surface areas disclosed herein aredetermined through this method. In one embodiment, the EC layersdisclosed herein have a specific surface area greater than 50 m²/g.

In some embodiments, one way to increase the specific surface are of theEC layer is through nanostructures. FIGS. 2B, 3A-3B, 5A-5B, and 8 showexemplary schematics of various nanostructured EC layers envisioned bythe disclosure.

The term “nanostructured” may mean having nanosized features, thenano-sized features including at least one dimension between 1 and 500nanometers. Nano-sized features include, but are not limited to,nanopores, nanospheres, nanograins, nanorods, nanoplatelets, andnanosized surface features, such as nanoridges, nanogrooves, andnanocolumns. In some embodiments, the nano-sized features may includenanoparticles. One way to determine the “size” of a feature is toconsider the smallest distance between two parallel planes that do notintersect the feature. For example, in FIG. 10A, the nanostructure has afeature size of 1001, not 1003. In some embodiments, the “smallestdistance” is measured in a direction parallel to the plane of a surfaceon which the feature is fabricated, i.e. the smallest distance is thewidth or length, not the thickness. For example, in FIG. 10B, the sizeof the feature is 1001, not 1003.

FIGS. 8A-8L show exemplary schematic nanostructured EC layers withnano-columnar structures 600 deposited on surface 300. FIGS. 3A and 3Balso show exemplary nanostructured EC layers with nano-columnarstructures. Surface 300 is preferably a surface of an electrode, but maybe the surface of any layer generally found in EC films stacks,including a surface of an ion-conducting layer or a surface of anintermediate ion-conducting layer. Additionally, it may also be thesurface of a substrate 6000, like the one disclosed above. Thesecolumnar structures have a features size that may be determined asdescribed above. For example, FIG. 8D has a feature size of 1001.

As seen in FIGS. 8C-8E and 8H, columnar structures include structureshaving variable widths or diameters along their length. Additionally,columnar structures 6000 may or may not be straight along their lengths.For example, some may have bends and curves along their lengths, as seenin FIGS. 8G and 8I-8L. Additionally, in some embodiments, they may alsohave protrusions extending from their length including fractal-likestructures, such as the structure seen in FIG. 8F. FIG. 8A showsstraight columnar structures (or pillars). FIG. 8B shows inclinedcolumnar structures. FIG. 8I shows a columnar structure with helix. FIG.8J shows a waved columnar structure. FIG. 8K shows a zig-zag columnarstructure. FIG. 8L shows a zig-zag columnar structure with varyingwidth. In some embodiments, columnar structures with greater surfacearea are preferred because a higher surface area allows for a largernumber of active sites for ion exchange. These columns may be straightwith protrusions or fractal-like structures along its length, like thestructure shown in FIG. 8F, or with variable diameters along theirlength. However, in other embodiments, the higher surface area providedby these structures are not needed and a straight “smooth” column, likethe one shown in FIG. 8A may be used.

Because columnar structures may include both structures that aregenerally straight and structures with bends and curves, there are twotypes of “lengths” that a columnar structure may have. One length is theapproximate length. The approximate length may be measured in a straightline, starting from the base of the column to the point of the columnthat is furthest away from the base. The base of the column is where thestructure meets the surface. The measurement is in the same direction asthe overall direction that the column extends from the surface 300. Forexample, a columnar structure similar to one shown in FIG. 8A hasapproximate length 602 a. Similarly, a columnar structure similar to theone shown in FIG. 8I has an approximate length 602 i. While column 600 imay have a zigzag configuration with bends along its length, the overalldirection of its extension from the surface 300 is vertical. As anotherexample, a columnar structure similar to one shown in FIG. 8b hasapproximate length 602 b. The overall direction that column 600 bextends from the surface 300 is at an angle.

On the other hand, the actual length of a columnar structure is nottaken in a straight lint but follows the bends and curves of thestructure. Thus, for columnar structures without bends or curves, theapproximate length is generally the same as the actual length, like inFIGS. 8A and 8B. In columnar structures with curves, the approximatelength is often times shorter than the actual length of the columnarstructure, like in FIGS. 8I and 8G.

The width of columnar structure may be measured where the column is atits widest point. The measurement is taken in a direction that isperpendicular to an imaginary line that bisects the column's actuallength. For example, the columnar structure in FIG. 8F has a width 601f. To determine whether a structure is “columnar”, the approximatelength is compared to the width. In some embodiments, columnarstructures 600 are structures having longer lengths than widths.

In preferred embodiments, an EC layer is comprised of more than one typeof columnar structure, like the ones shown in FIGS. 3A-3B. However, inother embodiments, an EC layer may be comprised of repetitive similarcolumnar structures, like those seen in FIGS. 8A-8L.

EC layers may also other various types of nanostructured featuresbesides columnar structures, such as nanopores, as seen in FIG. 5B, ornanorods, as seen in FIG. 5A. Additionally, EC layers may have a mixtureof different kinds of nanostructures, such as, for example, a mixture ofcolumnar structures and nanopores.

In some embodiments, the EC layers and films discussed above may be madeusing angle deposition. In other embodiments, they may be made usingelectrophoresis or electro-deposition. In yet some other embodiments,they may be made using atomic layer deposition. These methods providefaster and more efficient ways of fabricating these films as compared topatterning and etching of hulk films and are described below. Whilethese embodiments are described as individual methods, the EC layersdiscussed above may be made with a combination of one or more ofmethods.

Angle Deposition

In some embodiments, the EC layer 2000 may be made using angledeposition. Angle deposition may include oblique-angle deposition (OAD)and glancing-angle deposition (GLAD). In general, OAD and GLAD aredefined as evaporation or sputtering.

FIG. 1 illustrates a schematic of GLAD and OAD. With these depositiontechniques, an EC material 200 is deposited over a surface 300. Thedepositing of the EC material occurs by exposing the surface 300 to aflux 201 of the EC material 200 that is provided by source 100. In someembodiments, source 100 may be a magnetron.

In some embodiments, the EC material is selected from the groupincluding but not limited to tungsten oxide, nickel oxide, iridiumoxide, molybdenum oxide, vanadium oxide, and combinations thereof. In apreferred embodiment, the EC material comprises tungsten oxide. Thesematerials may or may not electro-chromic depending on their oxidationstate. One of ordinary skill in the art may be, however, to manipulatethe oxidation state of these materials to make these oxideselectro-chromic. For example, tungsten oxide, in its stoichiometricoxidation WO₃ state may not be electro-chromic. However, it may bemanipulated by decreasing its oxidation state. Thus, for example, WO_(X)where _(X) is 2.6 may be electro-chromic. In some embodiments, the ECmaterial 200 may comprise more than one EC material that areco-deposited at the same time. In other embodiments, the EC materialconsists essentially of a single electro-chromic material.

The surface 300 may held in place by can 302 that is controllable by auser. The surface 300 has a surface normal 301 that is perpendicular tothe plane of the surface 300. This is shown in FIGS. 1, 1A, 1B. As theflux 201 exits source 100 and travels towards the surface 300, ittravels in a first direction 202.

FIG. 1A is a close-up of the flux 201 and the first direction 202. Insome embodiments, the traveling direction of the flux 201 may berepresented as a single straight column. This means every portion of theflux 201 travels in the same direction and there are no directionaloutliers. However, in other embodiments, as shown in FIG. 1A, the flux201 may travel towards the surface 300 in one main direction but withportions of the flux traveling in directional outliers 203A-B. Thus, asused herein, the “first direction” 202 is the average direction traveledby the flux. For example, in FIG. 1A, the first direction 202 is takenas an average of all directions traveled by the flux, including 203A and203B.

As the flux 201 is deposited on the surface 300, flux 202 forms anincident angle with the surface normal 301. As used herein, “incidentangle” is the angle formed by the first direction of the flux and thesurface normal at the point of incident, or the point where the fluxmeets the surface. FIG. 1B shows a schematic drawing of the incidentangle.

The incident angle is at least 1 degree and at most 89 degrees, and maybe at least 1 degree and less than 10 degrees, at least 10 degrees andless than 80 degrees, and, preferably, at least 80 degrees and at most89 degrees. When the incident angle is between 1 degree and less than 80degrees, the technique may be referred to as oblique angle deposition(OAD). When the incident angle is between 80 degrees and less than 89degrees, the technique may be referred to as glancing angle deposition(GLAD).

A characteristic of OAD and GLAD is the development of columnarstructures 600 as seen in FIGS. 8A 8L. The origin of the columnarstructures lies in the specific nucleation step, followed by theanisotropic columnar growth greatly influenced by the so-calledatomic-scale ballistic shadowing and limited surface diffusion. DuringOAD or GLAD, the surface 300 experiences ballistic shadowing duringdeposition. Ballistic shadowing prevents flux from directly reaching theshadowed regions of the surface. This is shown in FIGS. 2A-2B.

FIG. 2A shows the initial nucleation stage at the beginning ofdeposition. This initial nucleation stage of EC layer growth roughensthe surface in a random manner. As the nuclei 204 form, the shadowingeffect will quickly become a determining factor in the EC layer growth.FIG. 2B shows progression of the deposition after the initial nucleationstage. A greater amount of material 200 is deposited onto the nuclei 204than into the shadowed area 303 of the surface 300. This disparity isonly increased as growth continues. Since only the tops of the nuclei204 receive flux 201, the nuclei 204 will develop into columns which maybe tilted in the direction of the incident flux. This is shown in FIG.2B.

The incident angle may contribute to the magnitude of the shadowingeffect. For example, at incident angles greater than 80 degrees, highshadowing effect may occur. In one embodiment, this high shadowingeffect may result in columnar structures that are slanted towards thesource of the flux. This is seen in FIG. 2B. In these embodiments, thecolumnar structures may form angle 700 with the surface normal 301.Thus, in this embodiment, the columnar structure is not parallel withsurface normal 301. As used herein, parallel may include being at least5 degrees off from one another. This angle may be smaller than theincident angle 400. This angle is the angle that the axis of rotation ofthe columnar structure makes with the surface normal. As the incidentangles decrease, the shadowing effect may also decrease. One of ordinaryskill in the art, with the benefit of this disclosure, may be able tomanipulate the incident angle to form the desired angle of the columnarstructure.

Additionally, in some embodiments, the surface 300 may be rotatedrelative to the flux to further generate and “design” variousmorphologies, like those seen in FIGS. 8C-8L, such as helixes, andzigzags. As used herein, “relative to the flux” means rotating eitherthe surface or the source of the flux in relation to the other. Thus,the source may be kept still while the surface is rotated by angle 500as shown in FIG. 1, the surface may be kept still while the source isrotated, or the surface and the source may both be rotated. In otherembodiments, the surface 300 is not rotated relative to the flux. Thedegree of rotation may include slow continuous rotation, fast continuousrotation, and discrete rotation (also known as discontinuous rotation).

FIG. 3A shows SEM images of WO_(x) EC layers deposited with an incidentangle of 85 degrees with slow surface rotation relative to the flux. Onecolumnar structure has a width of 601 at 480 nm and a height of 602 at4.7 μm. FIG. 3B shows an SEM image of another exemplary EC layer. Thematerial used was WOx, with an incident angle of 81.4 degrees and slowsurface rotation relative to the flux. The resulting columnar structuresmay be seen. One structure has a width 601 of 380 nm and a height of 2.6μm.

While nanostructures shown are columnar, OAD and GLAD may be used tocreate other types of nanostructures, as disclosed above.

Overall, the final nanostructure is a complex interplay of many factors,including but not limited to, the incident angle, the presence orabsence of substrate rotation, the type of rotation, substrate surfacetemperature during deposition, deposition rate, deposition power, andthe EC material that is deposited. For instance, the greater theincident angle, the greater the shadowing effect will be. If there is asubstrate rotation, then the resulting columns can have more structureson their surface and/or can be zig-zag structures. The substratetemperature affects the diffusion of the deposited particles; the higherthe temperature, the more pronounced diffusion of deposited particlesand more irregular structures can be expected than when the depositionis on substrate at room temperature. The nature of EC material affectsthe diffusion of the particles on the substrate (diffusion constant isan intrinsic property of each material). “Rougher” nanostructures can befabricated by faster deposition rates. By adjusting the deposition powerand rate, one can even control the type of nanostructures, e.g. columns,needles or grains. This includes not only the initial depositionparameters, but variation of those initial parameters during the courseof the deposition. For example, a change in the deposition rate duringthe deposition process may result in structures with varying widthsalong their actual lengths. As another example, if deposition startswith substrate rotation and the rotation is stopped during thedeposition process, the resulting structure may be thinner in the bottomand wider on top. Structures shown in FIGS. 8C, 8E, 8G, 8H, and 8L maybe the result of a variation of these parameters during the depositionprocess. In some embodiments, when the variation of the parametersoccurs near the end of the deposition process, the structures may beknown has having “capping layers.” The presence of these “cappinglayers” in the columnar structure indicate that a change in initialparameters may have occurred during deposition. One of ordinary skill inthe art, with the benefit of this disclosure will be able tosuccessfully apply vary these parameters to make the EC layers disclosedherein.

Further steps may be performed on EC layer and surface 300 after thedeposition of EC layer on surface 300 to further process EC layer.

In one embodiment, a first ion-conducting layer may be deposited overthe nanostructured EC layer. Additionally, a second ion-conducting layermay be deposited over the first ion-conducting layer after the firstion-conducting layer is deposited. This deposition may form an EC filmstack that may be incorporated to create an EC device.

In some embodiments, angle deposition as described above may be used toform two surfaces having electro-chromic layers. A first ion-conductinglayer is then deposited over the first nanostructured EC layer. Then, asecond ion-conducting is deposited over the second nanostructured layer.The first and second surfaces are then assembled such that the firstion-conducting layer and the second ion-conducting layer face each toform an electro-chromic system like the one shown in FIG. 9.

In one embodiment, this method may be combined with other methods suchas sol-gel, dip-coating, spin-coating, knife coating, annealing, andsintering to yield the nanostructured layer. In some embodiments, theseother methods may be post processing steps performed after thedeposition of the electro-chromic material by GLAD or OAD.

Electrophoresis or Electro-Depposition

In some embodiments, the EC layer 2000 as described above, along withthe different types of nanostructures as described above, may be madethrough electrophoresis or electro-deposition. Electrophoresis andelectro-deposition both comprise depositing an EC material 200 over asurface 300 using an applied electric field. The material migratesthrough the liquid towards the appropriate surface, usually the surfaceof an electrode.

Table 1 compares the two techniques and FIG. 4 shows a schematic of bothtechniques.

TABLE I Comparison of Electrophoretic and Electrolytic DepositionElectrophoretic Deposition Electrolytic Deposition Medium SuspensionSolution Moving Species Particles Ions or complexes Electrode ReactionsNone Electrogeneration of OH-and neutralization of cationic speciesPreferred Liquid Organic solvent Mixed solvent (water- organic) RequiredLow High Conductivity of Liquid Deposition Rate 1-10³ mm/min 10⁻³-1mm/min Deposit Thickness 1-10³ mm 10⁻³-10 mm Deposit Uniformity Limitedby size of particles On nm scale Deposit Controlled by stoichiometry Canbe controlled by Stoichiometry of powders used for use of precursorsdeposition

Electrophoresis may also be called electrophoretic deposition (EPD). Itis a technique where the charged particles in a solvent migrate underthe applied electric field supplied by power supply 800 and aredeposited onto a surface of an electrode 801 (also known as a conductivesurface). It a viable technique for creation of nanostructured layersand may be easily scaled-up for mass production.

FIG. 5A provides a schematic of EPD. As seen in FIG. 5A, the chargedparticles 205 migrate under an applied electric field towards surface ofanode 801A and is deposited on anode 801A to form a nanostructured EClayer. Although FIG. 5A shows Ni(OH)₂ as the EC material that becomesNiO when deposited, other EC materials may be used as known in the art.

In some embodiments, the EC material is selected from the groupincluding but not limited to tungsten oxide, nickel oxide, iridiumoxide, molybdenum oxide, vanadium oxide, and combinations thereof. In apreferred embodiment, the EC material comprises tungsten oxide. Thesematerials may or may not be electro-chromic depending on their oxidationstate or state in which they are introduced as a precursor. One ofordinary skill in the art may be, however, to manipulate the oxidationstate of these materials to make these oxides electro-chromic. Forexample, tungsten oxide, in its stoichiometric oxidation WO₃ state maynot be electro-chromic. However, it may be manipulated by decreasing itsoxidation state. Thus, for example, WO_(X) where _(X is) 2.6 may beelectro-chromic. In some embodiments, the EC material that is used maycomprise two EC materials that are co-deposited. In other embodiments,the EC material consists essentially of a single electro-chromicmaterial.

Although FIG. 5A shows a specific type of nanostructure, this is in onlyone embodiment, and EPD may be used to create any of to nanostructuresas described above. The final nanostructures that result from EPD are acomplex interplay of many factors, including but not limited to:deposition time and rate, particle size, pH of the solution, solventnature, surface conductivity, applied voltage, and suspensionconcentration. In one embodiment, the deposition thickness may becontrolled by a variation of deposition time, voltage, or currentdensity. In another embodiment, the deposition uniformity may becontrolled by the applied electric field. For instance the effects ofsome of these parameters on the final nanostructures are as follows: thehigher the deposition rate, the “rougher” structures, i.e. structureswith greater surface area are possible. Deposition time will of courseaffect the thickness of the final EC layer. The higher applied voltagewill result in higher deposition rate, and thus, rougher structures. Theparticle size and particle size distribution (if any), together with thedeposition rate, will affect the final nanostructures and porosity in EClayer.

One of ordinary skill in the art, with the benefit of this disclosurewould be able to manipulate these factors to arrive at the desirednanostructure layer.

Electro-deposition (ELD), also called electrolytic deposition orelectroplating, is another simple, fast, and inexpensive method fornanostructured layer fabrication. In one embodiment, it may be used tocreate EC layers with one EC material.

In another embodiment, it may be used to make EC layers with more thanEC material. A single material may be preferred in some situationsbecause using one deposition material simplifies fabrication costs. Inother situations, two or more materials may be preferred because itallows a blending of properties and achievement of overall layercharacteristics that may not be possible with one single EC material.For example, ELD may be used to co-deposit two or more materialsselected from the group of ceramic materials, metals, and polymers. Insome embodiments, at least two different types of materials areco-deposited. These nano-hybrid layers exhibit advantageous propertiescompared that may not be achieved with one material and/or othermethods.

A schematic of ELD is shown in FIG. 5B, where an EC nanostructured layerwith nanopores is created using ELD. In FIG. 5B, a precursor material1000 is first deposited in step 901. In one embodiment, this precursormaterial may be polystyrene. Other exemplary and non-limiting materialsinclude polymethacrylae, polyacrylate, and polyethylene. After theprecursor material is deposited, the electro chromic material 200, forexample, nickel oxy-hydroxyl, is deposited in step 902. The precursormaterial is then removed in step 903. This results in a nanostructuredEC layer with an open nanopore 210. Although FIG. 5B shows the precursormaterial as being a polystyrene sphere monolayer, other materials arewithin the scope of this disclosure. One of ordinary skill in the art,with the benefit of this disclosure would be able to manipulate thesefactors to arrive at the desired nanostructure layer. While FIG. 5Bshows a specific type of nanostructure, this is merely one embodiment,and ELD may be used to create any of the nanostructures as describedabove.

Overall, the resulting nanostructure is complex interaction of differentfactors, including but not limited to: deposition time and rate,particle size, pH of the solution, solvent nature, surface conductivity,applied voltage, and suspension concentration. For example, thedeposition uniformity may be controlled by the applied electric field.As another example, the deposition thickness may be controlled by avariation of deposition time, voltage, or current density. As yetanother example, the ON and OFF time in ELD may be varied to createnanostructured layers disclosed herein, including unique composition andnano-structure. This may be accomplished by varying the basicparameters, such as pulse peak current density and may be done in aversion of ELD called pulse electrodeposition. For instance the effectsof some of these parameters on the final nanostructures are as follows:the higher the deposition rate, the “rougher” structures, i.e.structures with greater surface area are possible. Deposition time willof course affect the thickness of the final EC layer. The higher appliedvoltage will result in higher deposition rate, and thus, rougherstructures. The particle size and particle size distribution (if any),together with the deposition rate, will affect the final nanostructuresand porosity in EC layer.

In one embodiment, ELD and EPD may be combined with other methods suchas sol-gel, dip-coating, spin-coating, knife coating, annealing, andsintering to yield the nanostructured layers. In some embodiments, theseother methods may be post processing steps performed after thedeposition of the electro-chromic material by ELD or EPD.

Atomic Layer Deposition

In another embodiment, the EC layer 2000 and surrounding ion-conductinglayer may be made using atomic layer deposition (ALD).

ALD refers to the method whereby the layer growth occurs by exposing thesurface to its starting materials alternately. ALD may be performed ator below atmospheric pressures. In comparison with chemical vapordeposition (CVD), while both ALD and CVD use chemical (molecular)precursors, the difference between the techniques is that the formeruses self-limiting chemical reactions to control in a very accurate waythe thickness and composition of the film deposited. In this regard, ALDcan be considered as taking the best of CVD (the use of molecularprecursors and atmospheric or low pressure) and molecular beam epitaxy(MBE=atom-by-atom growth and a high control over film thickness) andcombining them in a single method.

A schematic of ALD is shown in FIGS. 6A-6D. In FIG. 6A, a monolayer of aprecursor material is deposited over a first surface by exposing it to afirst gaseous precursor molecule (e.g. volatile compound of the element)in excess. During this step, the temperature and gas flow is adjusted sothat only one monolayer of the precursor material (also known as thefirst reactant) is chemisorbed onto the surface. In some embodiments,the excess of the reactant, which is in the gas phase or physisorbed onthe surface, is then purged out of the chamber with an inert gas pulse.In other embodiments, purging is not done. The surface is then exposedto a vapor reactant (also known as the second reactant). The secondreactant then chemisorbs and undergoes an exchange reaction with thefirst reactant on the surface in FIG. 6C. This results in the formationof a solid molecular nano-layer and a gaseous side product that may thenbe removed with an inert gas purge in FIG. 6D.

ALD may be used to form a nano-layer on the surface with relatively goodthickness control. In some embodiments, this nano-layer does notcomprise nanostructures and has a uniform thickness across the surfaceof deposition. In one embodiment, this uniform thickness may range fromless than 1 nm to a few nm thick. Because ALD may be useful in forminglayers with uniform thickness, it may be used in conjunction withanother method, such as those described above, to form an intermediateconformed layer deposited over the EC layer with nano-structure and highirregular features. Such a layer deposited by ALD may include theion-conducting layers 3000 as shown in FIG. 9.

In some embodiments, ALD may be used to form a nano-layer comprisingnanostructures for EC layers 3000. These EC layers may comprise similarnanostructures as discussed above. As such, the materials used in ALDmay be similar to those described in relation to the other methods forEC materials, or may be different materials, such as typical materialsused in ion-conducting layers including but not limited to metals, metaloxides, and polymers.

In one embodiment, this method may be combined with other methods suchas sol-gel, dip-coating, spin-coating, knife coating, annealing, andsintering to yield the nanolayers. In some embodiments, these othermethods may be post processing steps performed after the deposition ofthe nanolayer material by ALD.

It is appreciated that while these three methods are described as threeseparate embodiments, EC layer and EC films disclosed herein may bemanufactured using a combination of two or more of the describedtechniques. For example, FIGS. 7A-7C shows schematics of differentnanostructured EC layers. FIG. 7A shows an EC layer 2000 comprised of asingle EC material 200A. FIG. 7B shows an EC layer comprised of twodifferent materials 200A and 200B that were prepared with the sametechnique. For example the material may be undergoing the sametransition, cathodic or anodic coloration, and may be selected to be aninorganic oxide, PEDOT, viologen, or PB. FIG. 7C shows an EC layer madeof two materials 200A and 200B (dotted lines) prepared by two differenttechniques. In one embodiment, these materials may undergo the sametransition, cathodic or anodic coloration. FIG. 7C also shows an EClayer made of one material deposited by two different techniques (two200A, one represented by dotted lines). In one embodiment, the samematerial in FIG. 7C may be or without changes in the stoichiometry, suchas WO3 and WOx, where x is 2.7-2.9.

While some concepts are described herein with respect to only one of thefour methods, and these embodiments are described for an electro-chromicdevice, one of skilled in the art can readily understand that theseconcepts can also be applied to other types of devices requiringnanostructured layers and nano-layers.

The foregoing description of the specific embodiments will so fullyreveal the general nature of the invention that others can, by applyingknowledge within the skill of the art, readily modify and/or adapt forvarious applications such specific embodiments, without undueexperimentation, without departing from the general concept of thepresent invention. Therefore, such adaptations and modifications areintended to be within the meaning and range of equivalents of thedisclosed embodiments, based on the teaching and guidance presentedherein. It is to be understood that the phraseology or terminologyherein is for the purpose of description and not of limitation, suchthat the terminology or phraseology of the present specification is tobe interpreted by the skilled artisan in light of the teachings andguidance.

The breadth and scope of the present invention should not be limited byany of the above-described exemplary embodiments, but should be definedonly in accordance with the following claims and their equivalents.

1. A device, comprising: a pair of lenses; and an electro-chromic stackdisposed between the pair of lenses, comprising, in the order: a firstelectrode; a first nano-structured electro-chromic layer having a firstsurface that includes nanosized features of electro-chromic materialformed by angle deposition; an ion conducting layer; a secondnanostructured electro-chromic layer having a second surface thatincludes nanosized features of electro-chromic material formed by angledeposition; and a second electrode, wherein the first surface of thefirst electro-chromic layer and the second surface of the secondelectro-chromic layer face each other.
 2. The device of claim 1, whereinthe angle deposition is a glancing-angle deposition.
 3. The device ofclaim 1, wherein the angle deposition is an oblique-angle deposition.